A Stomata-like Metal Peptide Coordination Polymer

Stomatal transpiration performed by plant leaves,which was not only affected by external environment condition,but also by the regulation and control of plant itself.The process of transpiration has been identified as a method of climate regulation.The stomatal apparatus of leaves include two guard cells that open and close depending on whether the plants need to hold on to or lose water.It wound be significant to develop new materials with similar performance.The metal ion and organic linkers of porous coordination polymers(PCPs)make these materials show the contradictory properties,i.e.,stereo regularity and flexibility.Certain PCPs show considerable structural transformation in response to specific stimuli.In spite of that several examples of ’breathing’ PCPs have been reported,in which most of the structural change occurs without any bond breaking,cases of transformations in which part of bonds are broken and reformed are much rarer at the ambient condition.In light of recent developments of soft PCPs,we designed a new soft PCP and investigated the transformation mechanism on the following issues:In chaper 1,the development of soft PCPs was introduced.Moreover,the development of the stimuli used to trigger phase transitions and in situ analysis methods were mentioned.And the application of soft PCPs in recent years was introduced at last.In chaper 2,a flexible coordination polymer,Cu-(Gly-Thr)2H2O,was synthesized by careful choice of the peptide ligands.The transformation can be controlled by relative humidity,and it was found that the ordered transformation occurs with coordination bonds breaking and reforming without changing coordination numbers and valence of the copper ion.In chaper 3,this porous coordination polymer shows reversible single-crystal to single-crystal transformation with surprisingly high thermal stability.We also demonstrated that the transformation obeys domino effects and is driven by the flexible penta-coordinated copper ions and hydrogen bonding between water molecules and the pore wall of PCPs.In chaper 4,this reversible transformation makes it especially efficient at taking up CO2 under wet condition,which is similar to the function of plant stomata.